The metadata below describe the original scanning. Follow the "All Files: HTTP" link in the "View the book" box to the left to find XML files that contain more metadata about the original images and the derived formats (OCR results, PDF etc.). See also the What is the directory structure for the texts? FAQ for information about file content and naming conventions.
"Hertz's Miscellaneous papers form the first volume of his collected works, as edited by Dr. Philipp Lenard. The second volume is a reprint of his Researches on the propagation of electric action (already published in English under the title of Electric waves) The third volume consists of his Principles of mechanics, of which an English translation is now in the press."-Translator's note